1. Field of the Invention
The present invention relates to a display device array substrate and display device, and more particularly, to the structure of an array substrate which forms a display device such as a liquid crystal display device.
2. Description of the Related Art
Recently, many flat display devices, represented by liquid crystal display devices, use an active matrix driving system having thin-film transistors each of which functions as a switching element in each of the pixels arranged in a matrix. In display devices like this, the line resistance and line capacitance of lines for transferring signals such as video signals are increasing in accordance with the demands for large screens. This leads to insufficient charging of each pixel, and degrades the display quality. Therefore, it is essential to improve the capability of a signal line driving circuit for driving signal lines (i.e., for supplying predetermined video signals to signal lines).
If the capability of the signal line driving circuit is improved, however, IC chips included in the signal line driving circuit generate heat as the electric power increases. Also improving the capability of the signal line driving circuit complicates the circuit structure, and this increases the cost. Therefore, Jpn. Pat. Appln. KOKAI Publication No. 10-171412, for example, proposes a liquid crystal display device using a dot inversion driving system in which the structure of a signal line driving circuit is simplified. This reference discloses a technique which drives two rows of pixels with one signal line.
In this structure, however, two types of video signals different in polarity must be sequentially supplied to each signal line during one horizontal scanning period. It is also necessary to supply video signals having opposite polarities to each signal line in each horizontal scanning period. This increases the number of times of switching, and increases the load on the signal line driving circuit.